Mechanical actuators of various construction and design, such as linear actuators, are well-known in the art. A linear actuator generally transforms rotational motion into linear motion and typically includes a threaded elongated screw or nut component powered by a rotational motion source. The screw or nut movement is converted by a piston or other means to produce linear back and forth cyclic movement of an output member, such as for example, a sliding or elongated tube.
A conventional linear actuator includes an electric motor that rotates an elongated threaded screw shaft. Such a design is a screw mechanism for converting rotary torque motion into linear motion, e.g., a roller screw, a ball screw or an acme screw. Roller screws can carry heavy loads for thousands of hours in demanding and continuous-duty conditions. The exemplary application requirements and others can cause several inherent problems in operation.
Roller screw actuators are susceptible to high-energy demand, wear of individual parts, excess debris, and actuator failure. Many of the failure modes of mechanical and electromechanical actuators are caused by insufficient or failed lubrication, and an inability to manage wear debris in a programmed or systematic manner. Other drawbacks of roller screw actuators exist caused directly or in part by limitations of conventional lubrication systems.